Screen printing is an established way of creating designs on various substrates, where a stencil is formed by a screen, the screen is used to ink a substrate, and the substrate is then allowed to dry. Early versions of screen printing used silk stretched over a wooden frame to form the screen. A design was created by painting the screen with a greasy medium. The pores of the silk were then closed using a suitable gum. The pores of the silk in the areas covered by the greasy medium were not closed because the greasy medium rejected the gum. Thereafter, the greasy medium was washed away with a solvent, such as turpentine, if paint was used as the greasy medium, resulting in the corresponding areas becoming pervious to ink. The screen was then placed on the surface of the substrate to be decorated and ink was applied through the screen to the surface using a rubber squeegee. The ink soaked through the pervious areas of the silk and was imprinted on the substrate.
More recent versions of screen printing use fine mesh screen materials rather than silk. The chosen screen material is coated with a photographic emulsion. The photographic emulsion is exposed to a suitable source of light, with the image to be reproduced being located between the light and the emulsion. The light causes the emulsion to harden except in areas where the image is located. Thereafter, the screen is washed to remove the emulsion from the areas where it has not been hardened by the light, i.e., the image areas. The screen is then ready to be used as a stencil to print a design on a substrate.
A print screen including a stencil is mounted to be set down onto the material portion to be printed. The stencil is of a design, letter, number, etc., that is to be printed on the material when ink is moved across the screen by use of a squeegee that forces the ink through small pores in the stencil. As is known in the art, an automated screen print press is a piece of equipment that can mechanically apply ink through a silk screen onto a substrate, such as fabric. An automated screen print press provides mechanical material handling for processing material portions through a series of print heads, each of which performs a different screen print operation. Material portions are supported by a series of rotating pallets which sequentially position the material portions at the work stations. Then at one or more of the work stations, print heads installed on support arms are lower down to the material potions on the pallets.
The screen print press loads, unloads fabric portions, applies ink, and dries the applied ink in an assembly line fashion. The finished portion returns to the original station where loaded, so that it can be unloaded. The pallet is then reloaded with another fabric segment to be printed. An automated screen print press may comprise multiple heads from which separate colors are screen printed.
Laser equipment has also been used to scribe graphics on materials. In this process, a laser beam contacts a material and alters the physical and/or chemical properties of the material to scribe a graphic.